The objectives of this application are 1) to characterize the amount of molecular characteristics of nerve growth factor (NGF) and functionally similar factors in tissues which are innervated by the NGF-dependent sympathetic and sensory nervous systems, to permit evaluation of the functional role of such sources and 2) to characterize the molecular properties of the plasma membrane NGF receptor protein and the nature of the physical interaction of NGF receptor with the cytoskeleton in order to facilitate elucidation of the action mechanism of NGF. The specific aims related to the first objective are 1) to partially purify and to characterize the relationship to mouse 7S NGF of an NGF-like activity found in chick embryo iris, and to determine the developmental course of changes in amount of this material; 2) to purify to homogeneity and characterize a similar factor secreted by mouse L cells. The specific aims of the second objective are to determine the biochemical and functional relationship of kinetically slow and fast classes of NGF receptors on PC12 pheochromocytoma cells, to determine whether the cytoskeletal attachment of SLOW receptors is of functional significance, and to determine whether NGF receptors are associated with protein kinase activity. Our approach will involve studies of binding of 125I-labeled NGF to receptors on PC12 cells and PC12 plasma membranes, to detergent solubilized NGF receptor, and to NGF receptors inserted into naive cells by fusion of various cells with plasma membranes from PC12 cells. Purification and characterization of solubilized NGF receptors will be carried out, and we will attempt to prepare antibodies against NGF receptor by conventional techniques, and by monoclonal techniques.